Finding fall’s fish

When lake temperatures change in the late season, the fish scatter and get tougher to catch—unless you know where to look, and why

2Gord Pyzer

Imagine you’re a kid and your parents own a two-storey chocolate factory. During summer, you’re only allowed to play on the top floor, where some of the goodies are stored. But the door to the ground floor, where many of the finest treats are kept, is locked. Then in September, something wonderful happens: the bottom door is flung open and you’re allowed to roam throughout the building, stuffing your face with candy. It would be heaven. Well, that’s similar to what sportfish such as bass, black crappies, lake trout, muskies, northern pike, yellow perch and walleye experience in the fall. Just like the chocolate factory, when autumn rolls around, the entire lake becomes their playground—and their buffet.

With the fish so scattered, however, this change often makes locating them downright difficult for anglers. But that doesn’t have to be the case. To figure out how to find the fish, and how to change your fishing strategies accordingly, you need to understand the science of lakes.

cGord Pyzer

#1 Listen to the lake

In summer, lakes are stratified into a warm upper layer and a cold lower layer, with an extremely important barrier separating the two. This barrier is the “thermocline”—that thin band of water where the temperature rapidly drops. If you turn up the power on your sonar, you can clearly see the thermocline as a fuzzy, black band that’s eight to 12 feet thick.

For gamefish, this temperature barrier is virtually impassable. Warm- and cool-water fish such as bass, black crappies, muskies, northern pike, walleye and yellow perch are restricted to the layer above the thermocline. Think of this as the top floor of the chocolate factory. Cold-water-loving burbot, lake trout, salmon and whitefish, on the other hand, are locked into the lower level below the thermocline—the ground floor of the factory.

The thermocline layer also has another interesting property—it’s home to vast quantities of phytoplankton and zooplankton, which attract important forage fish such as alewives, shiners, smelts and especially ciscoes. Indeed, the thermocline is such a rich seam of food that biologists sometimes refer to it as the “ciscoe layer.” Because there are so many baitfish crammed into the narrow thermocline, warm-water fish living above it will swim down and dine along its upper edge. Similarly, cold-water species below will slide up and feast along the lower edge.

But in fall, nature mixes things up—literally. As autumn nights grow colder, the surface water cools. At first, it’s only the top few inches, but since cold water is heavier than warm water, this cooling water soon sinks and mixes with the water below, chilling it, too. This process is enough to begin chipping away at the thermocline layer.

The mixing is sped up even further by autumn breezes, which stir up the water, and ever-cooler evenings until the thermocline is completely dissipated. When that happens, the water temperature becomes consistent from the top to the bottom of the lake, creating the process we refer to as “fall turnover.” It’s also nature’s way of bringing oxygen-depleted water up from the bottom of the lake, and replacing it with oxygen-rich water from the surface.

As an angler, you need to appreciate that the fish are now free to roam and feed in every part of the lake, including those areas that were off limits to them all summer. The trick now is to figure out where the fish are likely to be feeding.

4Patrick Walsh

#2 Follow the changing forage

Since fall opens up so many new locations, you might think it’s daunting to find the fish. But it doesn’t have to be, as long as you remember that food is always the great equalizer. Find the food, and you find the fish. However, fall turnover means the food sources are also changing.

During summer, crayfish are a vital source of food for bass, walleye, yellow perch and even lake trout and northern pike. Come September, however, they begin to moult at the very same time turnover begins, shedding their hard, protective exoskeletons. Seemingly sensing they’re now more vulnerable, the crayfish secret themselves beneath structure such as rocks and logs to avoid being eaten.

It’s Mother Nature at her miraculous best, because at the same time she’s depriving shallow-water fish of this previously plentiful source of food, she serves up an entirely new menu item. In particular, as turnover progresses and the water continues to cool, baitfish become more available and an increasingly important source of sustenance.

Alewives, ciscoes, shiners and smelts spend the summer months in and around the thermocline because they favour its cool water temperatures. But since that layer has disappeared, these baitfish find the chilling shallow water more inviting with each passing day. So, as the likes of bass, black crappies, walleye and yellow perch drift toward deeper structures and cover, they cross paths with hordes of ciscoes, shiners and smelt that are migrating toward the shallows. Talk about a fortuitous collision course.

And guess what? It gets better still. The lake trout, salmon and whitefish that were bumping their heads against the underside of the thermocline all summer also start drifting toward shore in late autumn, in their case to spawn in the cold, shallow water. That’s why you can often catch a grand slam in the fall—a smallmouth bass, lake trout, northern pike and walleye on consecutive casts. I’ve done it many times.

2MInnesota DNR

Tasty favourites

Soft-rayed and high in protein, fall-spawning forage fish such as whitefish and ciscoes (above) are an incredibly important late-season food source for gamefish. Both whities and ciscoes, which are closely related, spawn at night on wind-exposed, wave-washed shorelines and shoals comprising coarse sand, gravel and broken rock. They typically favour water that’s less than 20 feet deep, with ciscoes venturing even shallower than whitefish. Whitefish lay their eggs first, when the water temperature reaches roughly 7°C. Ciscoes spawn in even colder, 4°C water, just before freeze-up. If you find these tasty silvery fish staging for the spawn, you can be sure the bass, lakers, muskies, pike and walleye are never far away.

aScott Gardner

#3 Watch the water temperature

Depending on where you live, turnover is usually completed by early to mid-October. At this point, your favourite lake should have a consistent water temperature from top to bottom, typically between 7°C and 12°C, depending on its depth. Shallower lakes undergo turnover earlier, and at warmer temperatures, than deeper, colder lakes. Regardless, fall turnover is now in full swing, aided by the wind and waves, and oxygen has been restored to the lake’s deeper basins.

As fall progresses, however, increasingly colder days and nights chill the surface waters faster than they can be mixed. When that happens, you start to find that the warmest water is increasingly deeper. Even more importantly, perhaps, is the fact that the water in the shallows goes through ever-greater daily fluctuations in temperature, from frigid lows at night to more moderate ranges during the day. When that happens, you can typically count on bass, black crappies, muskies, pike, walleye and yellow perch responding in two ways.

First, the fish will favour the stability associated with deeper main-lake structures in 20 to 40 feet of water, where the daily water temperature swings have little impact. So, these are prime areas for you to target. This doesn’t mean gamefish will avoid the shallows entirely, however. Bass, in particular, will scoot into waist- or even knee-deep water in the fall, but usually only during a spell of warm, unseasonable weather lasting more than two days. In certain situations, huge pike and muskies will also go shallow (see “Predator change-up" below).

The second response you can almost always count on is that the fish will frequent structure that provides a direct break between shallow and deep water, allowing them to move quickly to the surface or down deep without having to travel a long distance horizontally. One of my all-time favourite fall smallmouth locations, for example, is a rocky shoreline shoal that quickly drops from four feet of water to 38 down a 60-degree slope. If you fish it when the weather is overcast, windy and cold, you won’t get a bite. Come back after a half-dozen days of glorious, unseasonably warm weather, however, and the three- and four-pound smallies will slide up the slope in a matter of seconds and practically rip the rod from your hand. Find fast breaks like that and you’re in business.

bGord Pyzer

Predator change-up

In fall, most muskies and northern pike follow the fish crowds out onto ever-deeper structures, where the water is warmer and more stable. But some toothy critters love to break the rules. They’ll remain shallow and put up with the harsher conditions, attracted by the massive schools of ripe ciscoes and whitefish that are spawning at night on shallow, wave-washed, gravel-and-rock shorelines and reefs.

Several times, I’ve won the Molson Big Fish Contest by specifically targeting these massive, up-shallow fish as they feasted on staging spawners. In fact, it was on a mid-lake reef where ciscoes were spawning that I caught my personal-best muskie—a fish that, according to the length and girth formula, weighed 57½ pounds. Trolling a silver herring-like lure in seven feet of water, I hooked the giant during the last week of November in a blinding snowstorm.

eBob Sexton

#4 Search the deep structures

By late October and early November, the temperature of the surface water has typically dipped beyond the chilly phase and is plummeting toward downright cold. When this happens, you can often count on the best fishing of the fall season. Why? This is the time that bass, black crappies, muskies, northern pike, walleye and yellow perch establish late-fall and winter home ranges. Find these locations, and the fish will be there from one year to the next, unless they end up in the frying pan, of course.

In the fall, the fish are particularly attracted to deep structures, such as reefs, shoals and underwater points. And once turnover runs its course and the lake readies to freeze, the fish will move out to the very edge of those same structures. By then, the water in the deep basins below will be around 4°C, making it the warmest, most attractive water to the fish. To reach it, now all the fish have to do is go over the edge of the structure and slide down the steepest slope to the bottom.

One of my favourite mid- to late-November hot spots for both walleye and smallmouths provides a good example of this. The structure is so steep, I can carefully position my boat on the edge so that the transducer on the trolling motor shows me drop-shotting and jigging in 32 feet of water, while the transducer at the stern shows the basin of the lake lying 47 feet below.

Find such edges and you’re practically guaranteed success. Whether they’re headed to deep or shallow water, fall fish tend to take the fastest and most direct routes—just as you would when the chocolate factory’s doors are finally unlocked.

zGord Pyzer

Trolling trick

When you’re trolling for fall walleye, it’s important to first find the baitfish so you’re not fishing aimlessly. The baitfish schools are typically balled up, and often suspended off the edges of deep-water structures. When I find these bait balls, I carefully mark them on my GPS unit. Then I troll my lures—typically crankbaits—around the pods at the same depth. I’ll also employ snap weights and planer boards to spread out and precisely present my offerings.


Fishing editor Gord Pyzer stays on the water until ice-up, then starts sharpening his auger.